1. Field of the Invention
The present invention relates to a printer, and more specifically, the present invention discloses a printer that is capable of setting a calibration position within a range in which a print head is able to print a document.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a perspective view of a printer 10 disclosed in U.S. Pat. No. 5,861,726. The printer 10 comprises a housing 12, a carriage 14 installed inside the housing 12 that moves in right and left directions on a horizontal track 16, an ink container 18 installed on the carriage 14, a print head 20 set on the ink container 18, and a step motor 30 for driving the carriage 14. The printer 10 further comprises a light source 22, and a light sensor 24 installed outside a printing range of the printer 10. The carriage 14 further comprises a shield 26 for blocking light transmitted from the light source 22 to the light sensor 24.
The step motor 30 drives the carriage 14 to move left and right along the horizontal track 16, so that the print head 20 is able to print the document. Before the printer 10 starts to print the document, the printer 10 calibrates a position of the carriage 14 to a zeroed position, i.e. the position that the light source 22 and the light sensor 24 is at, outside of the printing range. The position of the carriage 14 is calibrated by using the step motor 30 to drive the carriage 14 to move until the shield 26 on the carriage 14 blocks the light transmitted from the light source 22 to the light sensor 24. When starting printing of the document, the step motor 30 drives the carriage 14 to a printing start point, so as to enter the printing range, then prints the document until printing is finished, or the next calibration time, at which time the position of the carriage 14 is zeroed again.
In the prior art printing method, the printer 10 is unable to detect immediately if the position of the print head 20 is not accurate, so the print head 20 continues printing on a wrong position, until the whole document is printed, or the next calibration. This wastes time and ink.
It is therefore a primary objective of the claimed invention to provide a printer that is capable of setting the calibration position inside the printing range. While not consuming excess time, the printer is able to detect the position of the print head in the printing process, so as to check whether the position of the print head is correct or not. If the error of the print head position is too large, then the printer is able to stop printing and calibrate the position of the carriage instantly, not wasting printing time and ink.
The claimed invention, briefly summarized, discloses a printer including a position detecting mechanism for detecting and calibrating a position of a carriage on a horizontal track, and a print head installed on the carriage for printing a document. The position detecting mechanism has a first portion installed at a calibration position of the horizontal track, and a second portion installed on the carriage. The calibration position is positioned within a document printing range of the print head, so that the second portion is capable of passing by the first portion during a printing process.
It is an advantage of the claimed invention that the printer has a position detecting mechanism installed within the printing range of the print head, so that the position of the carriage is detected and calibrated in the printing process. If an error of the print head position exceeds a predetermined range, but is within an acceptable range, the printer can calibrate the position of the carriage after printing the document. In contrast, if the position of the print head has a serious misalignment, then the printer may stop printing the document and calibrate the position of the carriage instantly, to avoid wasting printing time and ink.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.